1. Field of the Invention
The present invention relates to needle reshielding devices and more particularly relates to a device and a method for the removal and the replacement of a needle shield.
2. Description of Related Information
Hypodermic needles are used throughout the world for numerous purposes. Most commonly, they are used in conjunction with syringes to deliver medication to a patient or to an intravenous delivery system having a pierceable entry port. Hypodermic needles are also used with syringes for taking blood samples and in conjunction with evacuated tubes for taking blood samples.
A commercially available hypodermic needle generally consists of a needle shield and a needle assembly. The needle shield has an elongate body and an open proximal end. The needle assembly includes a hub having a passageway therethrough and a needle cannula projecting outwardly from the hub and having a lumen therethrough in fluid communication with the passageway. The hub may be a separate component or an integral part of the syringe barrel. In either case the needle shield usually frictionally engages the hub which many times has a frusto-conically shaped exterior surface to frictionally engage the inside diameter of the needle shield to hold the needle shield in place over the needle thus protecting the needle from damage from outside forces and protecting the user from accidental skin puncture by the needle.
At time of use the needle shield is removed exposing the sharp distal point of the needle cannula. Even before use, the sharp point of the needle can inflict minor injury if the user inadvertently sticks himself or herself. After use the sharpened needle tip poses an additional problem because it may be contaminated and be an instrument for the inadvertent transfer of infection or disease. Many hospitals require reporting of all accidental needle sticks so that even an incident with a clean sterile needle is a reportable incident requiring expenditure of time and money.
Great effort has been expended to minimize the possibility of inadvertent needle sticks. Inadvertent needle sticks can happen during the act of reshielding as the user attempts to guide the sharp needle into the small diameter proximal opening of the needle shield so that the needle shield re-engages the hub. The user may miss the needle shield and stick his or her own hand. It is the belief of some that needle re-shielding should not be attempted and the used hypodermic needle should be disposed of immediately. In many applications this type of disposal may not be practical if the disposal apparatus or means is not in the area where the hypodermic needle is being used. Others recommend cautious re-shielding by one-handed techniques or one-handed devices or two-handed techniques using devices having projections for shielding the user's hand and/or for guiding the needle toward the needle shield interior.
U.S. Pat. No. 4,717,386 to Simmons teaches a device for uncapping and capping the protective sheath of a hypodermic needle. In one embodiment, Simmons provides a hand-held shield to isolate the fingers from the sheath and to provide a barrier to protect the user in case the needle misses the opening in the sheath upon reassembly. Reshielding devices such as these must be carefully designed and carefully used. The shield material must be strong enough to prevent the needle from penetrating all the way through to the user's hands yet not hard enough that the needle would slide off the shield into the user's hand. Although this embodiment of Simmons' device greatly reduces the chance of needle stick it does not eliminate it. Simmons teaches another embodiment which is attached to a work surface providing one-handed uncapping and re-capping. Both embodiments of Simmons appear to work by frictionally engaging the exterior of the sheath to hold the sheath with greater force than the resisting force of the sheaths frictional engagement to the tapered needle mount of the syringe.
U.S. Pat. No. 4,742,910 to Staebler also enables a needle sheath holder which can be hand-held or set in a stand or a test tube rack. The needle sheath holder frictionally engages the needle sheath through the deflection of a plurality of gripper members in a gripping assembly. It is unclear if the needle sheath can be removed from the holder by applying forces to the syringe without disengaging the needle sheath from the syringe or if Staebler intends that the needle sheath remain permanently in the holder.
U.S. Pat. No. Des. 302,295 to Hanifl et al. illustrates a needle resheather. This needle resheather appears to rely on frictional engagement with the sheath and because of its right angle structure appears to be mountable on either of its two sides or in a corner.
The needle sheath holding device of Simmons, Staebler and Hanifl et al. undesirably rely on frictional engagement of the needle sheath. Frictional engagement is not desirable because increasing the axial force on the hypodermic syringe to engage the sheath in the holder not only tightens the grip of the holder on the sheath also increases the frictional engagement force of the sheath to the needle hub. Increasing forces to engage require increasing forces to withdraw the syringe from the needle sheath which may require such an amount of force as to cause the assembly to abruptly come apart and injuring the user. It would be desirable if the forces used to engage the needle sheath into the holder did not also make it more difficult for the needle to be removed from the sheath. Also, the use for friction for engagement can result in a system which acts differently with every use. Higher engagement forces for the sheath into the holder result in higher removal forces necessary to expose the needle for use. Also final removal of the needle sheath from the holder may be difficult.
U.S. Pat. No. 4,737,149 to Gillilan also teaches a device for the removal or attachment of a needle sheath to a needle assembly using resilient material to frictionally engage the needle shield. Gillilan has an apparent advantage over other friction devices that rely on friction to hold the needle shield in that structure to assist in ejecting the needle shield from the device is taught.
U.S. Pat. No. 4,979,945 to Wade et al. teaches a syringe needle cap resheathing and removal apparatus capable of single-handed operation for three different standard needle cap shapes. The device of Wade et al. provides a lateral recess of varying shape to accept several types of needle caps and hold them in position through the shape of the side walls along the lateral recess and the cantilever flexing of one of the members to apply a frictional grip on the needle shield. In the Wade et al. device the force used to engage and remove the needle cap from the apparatus is directed perpendicularly to the axis of the needle cap.
A syringe scabbard sold by Syringe Scabbard Systems of Lyndhurst, Ohio is a device for one-handed unshielding and re-shielding which is provided with an adhesive base to adhere it to a work surface. A syringe scabbard device apparently relies on a claw-shaped lip to engage the proximal surface of the needle shield so that the syringe may be withdrawn while the needle shield is retained in the device. This device does not appear to rely on axially applied frictional forces to engage the needle shield in he device. Apparently there is enough space in the Syringe Scabbard device to allow for re-shielding and removal without engaging the lip. A device such as this may present problems in that it appears that the claw-shaped lip may also be capable of removing the hypodermic needle from syringes which do not have the locking luer feature. Also the Syringe Scabbard device does not appear to hold the needle shield after removal but just to provide a restrained storage area wherein the needle shield may move around making re-shielding a more difficult time-consuming procedure since the shield is not restrained from lateral motion.
Although the art has provided improved devices to facilitate the removal and re-engagement of needle shields while lowering the possibility of accidental needle sticks there is still a need for a simple, straight-forward, reliable, easily fabricated device for the removal and replacement of a needle shield which holds the needle shield in a releasably secure position without relying on axially applied frictional forces to engage the needle shield in the device. There is also a need for a device for the removal and replacement of a needle shield which will accommodate commercially available needle shields without alteration of the needle shields.